Reducing tourist carbon footprint through strategic mapping of the existing hotel stock – Attica

The tourist carbon footprint (TCF) is the measure of the total amount of carbon dioxide (CO ₂) tourists emit by travelling from origin to destination and by participating in tourism – and leisure – related activities considering all relevant sources, sinks and storage within the spatial boundary of the destination. This paper presents a method of assessing the part of TCF associated with tourist transport at the tourist destination and proposes iso-pollutant contours as the most effective method of mapping TFC in relation to hotel location by using the prefecture of Attica in Greece as an example. The paper demonstrates for the first time how important is hotel location as a determinant factor of TCF and also proposes measures to reduce CO ₂ emissions through the implementation of policies that are environmentally friendly and are aiming to facilitate the transport of the tourists and promote the use of public transport.     

A mathematical model of subpopulation kinetics for the deconvolution of leukaemia heterogeneity

Acute myeloid leukaemia is characterized by marked inter- and intra-patient heterogeneity, the identification of which is critical for the design of personalized treatments. Heterogeneity of leukaemic cells is determined by mutations which ultimately affect the cell cycle. We have developed and validated a biologically relevant, mathematical model of the cell cycle based on unique cell-cycle signatures, defined by duration of cell-cycle phases and cyclin profiles as determined by flow cytometry, for three leukaemia cell lines. The model was discretized for the different phases in their respective progress variables (cyclins and DNA), resulting in a set of time-dependent ordinary differential equations. Cell-cycle phase distribution and cyclin concentration profiles were validated against population chase experiments. Heterogeneity was simulated in culture by combining the three cell lines in a blinded experimental set-up. Based on individual kinetics, the model was capable of identifying and quantifying cellular heterogeneity. When supplying the initial conditions only, the model predicted future cell population dynamics and estimated the previous heterogeneous composition of cells. Identification of heterogeneous leukaemia clones at diagnosis and post-treatment using such a mathematical platform has the potential to predict multiple future outcomes in response to induction and consolidation chemotherapy as well as relapse kinetics.     

Efficient tracking using a robust motion estimation technique

Camera based supervision is a critical part of event detection and analysis applications. However, visual tracking still remains one of the biggest challenges in the area of computer vision, although it has been extensively discussed during in the previous years. In this paper we propose a robust tracking approach based on object flow, which is a motion model for estimating both the displacement and the direction of an object of interest. In addition, an observation model that utilizes a generative prior is adopted to tackle the pitfalls that derive from the appearance changes of the object under study. The efficiency of our technique is demonstrated using sequences captured in a complex industrial environment. The experimental results show that the proposed algorithm is sound, yielding improved performance in comparison with other tracking approaches.     

Effect of Non-Ionic Surfactants and Beta-Ionone on the Morphology of Blakeslea trispora and Carotenoids Production from Cheese Whey in Submerged Aerobic Growth: A Statistical Approach

The effect of non-ionic surfactants and β-ionone on morphology of Blakeslea trispora and carotenoids production from deproteinized hydrolyzed whey in submerged aerobic growth was investigated. Also, a central composite design was employed to determine the maximum carotenoids concentration at optimum values for the process variables (Tween 80, Span 80, β-ionone). The fit of the model was found to be good. Tween 80 and Span 80 had a strong linear effect on carotenoids production. The concentration of carotenoids was significantly affected by Tween 80 – Span 80 and Span 80 – β-ionone interactions as well as by the negative quadratic effect of β-ionone. The optimum medium composition for the maximum carotenoids production (100.0 ± 5.0 mg/g biomass dry weight) was found in deproteinized hydrolyzed whey supplemented with Tween 80 (33.6 g/L), Span 80 (68.7 g/L), and β-ionone (2.6 g/L). This result indicated that the optimization strategy led to an increase in carotenoids production by 33-fold. The carotenoids content in B. trispora were β-carotene, γ-carotene, and lycopene. The composition of carotenoids depends of the amount of nonionic surfactants and β-ionone added to the cheese whey. The medium composition influenced the morphogenesis of B. trispora and product formation. The addition of surfactants into the medium changed the morphology of the microorganism from solid aggregates to loose aggregates and resulted in a substantial increase in pigment production. B. trispora growing in submerged aerobic growth is able to develop complex morphologies which have been classified into three major groups: freely dispersed hyphae, clumps, and pellets. These parameters are responsible for the production of carotenoids.     

Experimental study of combustion noise radiation during transient turbocharged diesel engine operation

Diesel engine noise radiation has drawn increased attention in recent years since it is associated with the passengers’ and pedestrians’ discomfort, a fact that has been acknowledged by the manufacturers and the legislation in many countries. In the current study, experimental tests were conducted on a truck, turbocharged diesel engine in order to investigate the mechanism of combustion noise emission under various transient schedules experienced during daily driving conditions, namely acceleration and load increase. To this aim, a fully instrumented test bed was set up in order to capture the development of key engine and turbocharger variables during the transient events. Analytical diagrams are provided to explain the behavior of combustion noise radiation in conjunction with cylinder pressure (spectrum), turbocharger and governor/fuel pump response. Turbocharger lag was found to be the main cause for the noise spikes during all test cases examined, with the engine injection timing calibration and the slow adjustment of cylinder wall temperature to the new fueling conditions playing a vital role. The analysis was extended with a quasi-steady approximation of transient combustion noise using steady-state maps, in order to better highlight the effect of dynamic engine operation on combustion noise emissions.     

On the Scarcity Value of Irrigation Water: Juxtaposing Two Market Estimating Approaches

The aim of this paper is to compare the supply-side and demand-side approaches for assessing the scarcity rents of irrigation water. The results obtained from the case study confirm the expectation that the demand-side rationale provides the lower bound estimate of water scarcity rents. Specifically, a hypothetical elimination of water scarcity brings extra benefits to the local farmers, but these benefits cannot compensate the costs of the backstop technology which provide such extra water. Therefore, the lost opportunities, in terms of income forgone due to water scarcity, cannot legitimize supply-side approaches alone. A “soft” sensitivity analysis was included to examine the robustness of such a cost-effective property, while the policy implications of the results are also examined.     

Biogas production from energy crops in northern Greece: economics of electricity generation associated with heat recovery in a greenhouse

Herein a techno-economic assessment was performed on an energy-crop-based biogas plant coupled with a greenhouse for utilizing thermal energy produced by cogeneration. Seven energy crops were evaluated: triticale, maize, alfalfa, sunflower, clover, barley and wheat. According to the evaluation, triticale was the most competitive energy crop under selected climate conditions for northern Greece. Although maize displays higher biomass yield and biogas potential than the drought-resistant crop triticale, it has high irrigation demand that contributes significantly to total production costs. For a triticale-based biogas production to become economically feasible, agricultural arable area larger than 500 ha, or biogas plant size larger than 1000 kW_el, is required. However, with public funding, biogas production becomes feasible at smaller area (>250 ha) or biogas plant size (>500 kW_el). The inclusion of a greenhouse into the design of the biogas plant contributes positively to the economic viability of the entire system. Under this scenario, greenhouse financial income accounts for about 17–18% of total income. Results of a sensitivity analysis suggest that the selection of an appropriate energy crop for biogas production should be based principally on both digestibility (specific methane yield) and biomass yield per hectare, these factors being more critical than biomass production costs.